This application relates to a gas turbine engine having a lower pressure air flow path selectively driven across a boost compressor.
Gas turbine engines are known and include a fan delivering air into a bypass duct and into a core engine compressor. The bypass duct air flow path is utilized as propulsion and the core air flow path in the compressor is compressed, mixed with fuel in a combustor, and ignited. Products of this combustion pass downstream over turbine rotors, driving them to rotate.
In some applications and, in particular, in military applications, the ability to provide adaptive performance including the generation of very high thrust in a very short period of time is desirable. In one proposed engine of this type, a secondary mid-fan supplied third air flow path is provided, which is at a lower pressure than the fan discharge supplied primary bypass air flow path.
This third air flow path may be utilized for various lower pressure applications, such as cooling. However, this third air flow path is at a relatively low pressure, particularly when compared to the pressure in an exhaust nozzle. As such, downstream uses for this third air flow path are limited.